This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Heparin is well-known for its anticoagulant activity based on its ability to accelerate the rate at which antithrombin inhibits serine proteases in the blood coagulation cascade. Heparin is a linear polymer consisting of repeating units of 1[unreadable]4 linked pyranosyluronic acid and glucosamine residues and contains many sulfo groups that give it a high negative charge. NMR is a powerful technique capable of studying the structure of glycosaminoglycans without prior chemical or enzymatic cleavage into smaller oligosaccharides. Thus, NMR can be used to avoid the loss of structural information that results when the polysaccharides are broken down to smaller oligosaccharides. Here we performed proton and carbon 13 NMR to study the structure of heparin and the difference among different preparative lots.